Over the past few years a wide variety of styles and configurations of steam cleaners and pressure washers have been introduced onto the market. Basically, these pressure washers are all adapted to force water out of an exit nozzle under pressure. Such steam cleaners and pressure washers are used for various purposes, such as cleaning vehicles, heavy equipment, buildings, food preparation equipment (e.g., kettles, cutting instruments), etc. Some of such steam cleaners and pressure washers are adapted to heat the water to 210 degrees, some to 325 degrees, and some to higher temperatures, before it is forced out of the nozzle, while other such washers are adapted to force the water out of the nozzle without heating.
The water is heated by forcing it (e.g., by a pump) through a coiled tube. Coils are designed to help form a combustion chamber and to let the exhaust gases escape out of the stack. Coils are usually made of steel pipe welded together or they may be made of continuous tubing. The greater the number of wraps and the number of feet in the coil, the greater the extent to which the water is heated in the coils, for a given burner.
The heating of water in the coiled pipe can cause the interior surface of the pipe to rust and, in hard water areas of the country, heating of the water in the coils can cook the minerals out of the water. As a result, the minerals may be caused to stick to the interior surface of the coiled pipe (e.g., resulting in a lime build-up in the pipe). Some types of soap and chemicals can cause the same type of problem, creating a coating or scale on the interior surface of the pipe in the coil.
Lime or chemical deposits in the coiled pipe will cause a decrease in the water flow through the pipe, reduce the outlet temperature and pressure of water from the coil, and may eventually plug the coil. Restriction in the coil, whether by lime build-up or other chemical deposition, will cause the water pump outlet pressure to be higher than the outlet pressure from the coil (e.g., by as much as 350 psi or more).
The burner used to heat the water may burn fuel oil or LP or natural gas. The more water that is forced through the coil, the more heat or BTUs it takes to heat the water. Some coils which are 105 feet long will heat 2 gallon per minute (gpm) of water up to 325.degree. F. and burn 1.25 to 1.5 gallons per hour of fuel. Some steam cleaners and hot pressure washers with a 105 feet coil can heat 4 gallons per minute of water to 160.degree. F. and burn 4.75 gallons of fuel per hour.
If the burner fails to light, the combustion chamber can fill with fuel oil or gas and possibly explode. Poor grades of fuel oil or inadequate combustion air can cause heavy soot build-up on the outer surface of the heating coil. It will restrict air flow through the coil and out of the stack, further aggravating the soot build-up.
Steam cleaners and hot water pressure washers are commercially available with a vertical or a horizontal fired heater, having various capacities, i.e., some washers are capable of heating and supplying water at a rate of about two gallons per minute, while other washers may be capable of heating and supplying water at a rate of ten gallons per minute or more (e.g., 30 gallons per minute). In other words, some steam cleaners and pressure washers consume more power and burn more fuel than others.
Some high pressure washers and steam cleaners utilize gasoline or diesel engines as a power source. For example, the gasoline or diesel engine may power a generator to provide electrical power for the pressure washer, or the engine may power the water pump directly, or the engine may power both the generator and the water pump. The more water being forced through the washer, and the greater the pressure of the water exiting the washer, the larger the water pump, the electric motor, or gasoline or diesel engine which is required. Failing to use a larger pump or motor may result in the motor pump, and electric system being overloaded.
The electrical system of a steam cleaner or pressure washer includes an electrical power cord to manual on-off switches to the electric motor (if used), from manual on-off switch to burner assembly on-off switch, then through the burner assembly (either fuel oil or LP or natural gas), through a thermostat switch (if used), then through a flow, vacuum, or pressure switch (if used); and sometimes a stepdown transformer is used (e.g., 440 volts to 220 volts, etc.)
Most pressure washers which use a trigger control gun include a bypass or unloader valve adapted to bypass water back into the water pump inlet when the trigger is in a closed position (to shut off the water from the exit nozzle). This causes a flow, vacuum, or pressure switch to sense that there is no water flow or pressure, and consequently an electric switch is opened to turn off the burner assembly or fuel solenoid valve (if used) on the fuel pump. Some pressure washers wire flow or pressure switches to turn the water pump motor and burner assembly off, but if there is a leak in a pressure hose to the exit nozzle, the pressure washer will come on by itself.
The power cord on a steam cleaner or pressure washer is usually adapted for 120 volt or 240 volt, single phase 10/3 to 18/3. The first numbers denote the gauge of wire (the larger the number, the smaller the wire). The last number denotes the amount of wire in the cord. In power cords having three wires the wires are green, black and white, respectively. For 3 phase power cord, it also has red (i.e., 10/4 etc.) and is from four inches long to five feet long. Most steam cleaners or pressure washers have only a short lead-in cord. Consequently, when using such devices it is necessary to use an extension cord to connect to the lead-in cord. If the lead-in cord is sufficiently long to reach the floor, and if there is water on the floor, it is possible that the lead-in cord could lay in the water and cause an electrical shock.
The burner assembly has an electrical blower motor and a transformer which converts 120 volt or 240 volt primary voltage to 10,000 volts (secondary voltage), wired parallel together and into a series with a thermostat, flow or pressure switch, and an on-off switch. If a fuel solenoid valve is used, it is wired in series with the thermostat, flow or pressure switch back to the burner switch, blower motor and transformer; then it is wired back to a manual on-off switch, blower motor and transformer; then it is wired back to a manual on-off switch. The blower motor turns the fan (to provide air for the combustion chamber) and powers the fuel pump. The transformer is adapted to connect to electrodes by a buss bar, appropriately adjusted so that electricity arcs across the electrode tips and thereby lights fuel in the chamber. An LP or natural gas assembly is wired in series with a temperature flow pressure switch to a gas valve or safety regulator.
In those steam cleaners or pressure washers with a thermostat, the thermostat also can turn off the on-off switch for the burner assembly or fuel solenoid valve. Some thermostats are non-adjustable (i.e., pre-set by manufacturer). Some are adjustable and include a dial to set the water outlet temperature. Some steam cleaners or pressure washers use thermostats that have a sensor bulb in the coil outlet water line and are connected to an electric automatic on-off switch, while others have automatic on-off switches connected to sensors which are attached to the coil outlet pipe. When a flow or vacuum switch is used, water flows through a housing assembly connected to an electric switch; this apparatus is adapted to shut off the inlet water. When a pressure switch is used, an electric on-off switch is contained in a housing installed between the water pump outlet and the by-pass or unloader valve.
A few steam cleaners and pressure-washers use electronic controls which regulate temperature, flow or pressure switch, or fuel solenoid, etc. to turn the burners off automatically.
Those steam cleaners and pressure washers which use a straight through gun-wand assembly don't have a trigger gun, or flow or pressure switches, or by-pass valves, etc. Cold water pressure washers don't use heating coils, thermostats, flow or pressure switches, etc.
Some steam cleaners or pressure washers use safety controls, such as trigger control guns, or pop-off or relief valves which are set to relieve water or steam into the atmosphere or into a float tank at a pre-set pressure or temperature. Some steam cleaners or pressure washers use a float tank between the water inlet and the water pump. A few steam cleaners use a lead melt-out device which melts if the water gets too hot or has too much pressure. Steam cleaners heat the water to create pressurized steam, and hot water pressure washers heat water under pressure.
It has been found that some pressure washers and steam cleaners are more efficient than others. It has also been found that some pressure washers and steam cleaners emit more hydrocarbons than others, i.e., some combustion heaters burn more efficiently than others. Other operating parameters also vary from one type of steam cleaner or pressure-washer to another, with many different styles and configurations and a variance in the quality of components (motors, pumps, switches, unloader valves, etc.) used in the manufacture of such equipment.
Unfortunately, there has not heretofore been provided any convenient and reliable means to analyze the operating parameters of various pressure washers. Consequently, it has been difficult to analyze all of the operating parameters of a particular pressure washer, and it has been even more difficult to analyze and compare operating parameters of competitive pressure washers. Although there have been a variety of various hand-held gauges or meters available (e.g., voltmeters, pressure gauges, etc.) for measuring a specific parameter, such individual gauges or meters are rather inconvenient and time consuming to use while attempting adjustments to the apparatus. Moreover, the use of a single measuring instrument at a time is not a reliable way to analyze all of the operating parameters of such apparatus. Furthermore, it is not possible to simultaneously measure or analyze all of the operating parameters of such apparatus under varying conditions using hand-held individual gauges or meters.
Consequently, it has been extremely difficult for service repairmen and manufacturers to accurately and efficiently analyze all of the operating parameters of a particular steam cleaner or pressure washer. Yet, without an accurate analysis of such operating parameters, it is very difficult for a repairman to make correct repairs or adjustments to a piece of this equipment, and it has been even more difficult to analyze and compare operating parameters of competitive steam cleaners or pressure washers. Of course, it has also been impossible to set meaningful standards for the design and manufacture of this type of equipment.